Loading ...
Sorry, an error occurred while loading the content.

Re: GPS Referenced RXTX for WSPR

Expand Messages
  • warrenallgyer
    Miura-san I am very interested in this product. I have sent you a private email to discuss. Best regards, Warren Allgyer - 9V1TD
    Message 1 of 21 , May 21, 2013
    • 0 Attachment
      Miura-san

      I am very interested in this product. I have sent you a private email to discuss.

      Best regards,

      Warren Allgyer - 9V1TD

      --- In softrock40@yahoogroups.com, "netnovel2005" <ja7tdo@...> wrote:
      >
      > Hello,
      >
      > I made GPS stabilized Soft66GPS few years ago.
      > WI125 is compact easy module.
      >
      > http://zao.jp/radio/GPS/
      >
      > WI125 can be used another RX TX.
      >
      > vy73
      > JA7TDO
      > Miura
      >
    • Alan
      ... Subject: [softrock40] GPS Referenced RXTX for WSPR ... Warren, A few comments, not really relavent to your post but more to Softrock stability. I d rather
      Message 2 of 21 , May 22, 2013
      • 0 Attachment
        ----- Original Message -----
        Subject: [softrock40] GPS Referenced RXTX for WSPR


        > The Si5170 based radios tend to wander a bit in frequency based on ambient temperature. My shack is not air conditioned when I am
        > not inside and the difference in my WSPR frequency can be 10-12 Hz depending on the state of the air con.
        >
        > I have built a GPS referenced signal generator based on the Si 5338 Evaluation board. By coupling it with a uBlox GPS module that
        > has a programmable, GPS disciplined output, I have four separate outputs, referenced to GPS, each with a programmable frequency
        > range of about 3.0 to 700 MHz.
        >

        Warren,

        A few comments, not really relavent to your post but more to Softrock stability.

        I'd rather not join yet another group but would like to see your picture.

        I've used GPS as a reference since I found the old Rockwells with a 10KHz output. But for almost every HF purpose I think GPS is
        overkill.
        Since I tried some modern OCXOs I have abandoned GPS.
        A 10MHz one I have was setup a long time ago and is still within 0.1Hz of a GPS reference.
        I used a 67MHz OCXO, doubled, as a reference for a 9850 DDS with similar results.
        I've never tried locking a Softrock, but there must be other DDS that will produce suitable frequencies.

        I'm again reminded of Fred's suggested software solution. Use a reference to compare the "dialled frequency" with the actual
        frequency and adjust the Si570 to suit. It seems no-one has accepted that challenge.

        My Softrock experiments all involve separating the Si570 from the Softrock so go against your minimal interference policy.
        I made some improvement by putting the Si570 in an oven. I realised afterwards that I was probably being too cautious 40-50° was too
        low. The internal temperature of a Si570 is going to be higher than that.
        A few years ago there was discussion here, several tried thermistors on the Si570 case. I do not remember anyone giving details of
        their results.

        In my moderate environment my Softrock is generally stable enough, maybe +/- 5Hz on 10m over the range of temperature I experience.
        This seemed fine for WSPR with 2 minute TX periods.
        But when I tried WSPR-15 on my old Softrock 6.3 there was too much drift, about 4Hz on 160m in 15 minutes of TX.
        I eventually realised that heat from the regulator and PA was travelling along the board. I removed the Si570 and wrapped it with
        insulation. Not quite a simple as it sounds but no short-term drift.

        73 Alan G4ZFQ




        > My goal has been to modify an RXTX to accept one of these programmable outputs, replacing the onboard Si5170. I wanted to do it in
        > a reversible manner with as little disruption or damage to the board as possible, especially in the prototype.
        >
        > A picture of the prototype is posted here:
        > http://groups.yahoo.com/group/sdr-users/photos/album/163267873/pic/1779345030/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc
        >
        > I replicated T1 and R12, along with a SPDT slide switch on a 0.6 x 1.0 in. piece of perf board. I removed C3. A new wire from the
        > T1 side of the C3 holes goes to one pole of the switch. The output of the new T1A goes to the other side, and a new C3 connects
        > the center pole of the switch to the old C3 hole on the output. I picked up a ground on the ground side of the opto isolator. The
        > new RF input is connected to the primary side of the new T1A.
        >
        > The slide switch now selects the onboard Si5170 or the new external input via the new transformer. I set the whole board in a
        > puddle of clear silicone so no holes were drilled.
        >
      • warrenallgyer
        Sorry Alan... I was not aware that you had to join the group to see the picture. For some reason the photo server on this group seems to be down at the moment.
        Message 3 of 21 , May 22, 2013
        • 0 Attachment
          Sorry Alan... I was not aware that you had to join the group to see the picture. For some reason the photo server on this group seems to be down at the moment. Not much to look at but here it is:

        • warrenallgyer
          Sorry Alan... I was not aware that you had to join the group to see the picture. For some reason the photo server on this group seems to be down at the moment.
          Message 4 of 21 , May 22, 2013
          • 0 Attachment
            Sorry Alan... I was not aware that you had to join the group to see the picture. For some reason the photo server on this group seems to be down at the moment. Not much to look at but here it is:

          • vbifyz
            I tried ovenizing the Softrock (VHF version) without removing the Si570. The thermistor was taped to the Si570 case and the heating resistor to the empty
            Message 5 of 21 , May 22, 2013
            • 0 Attachment
              I tried "ovenizing" the Softrock (VHF version) without removing the Si570. The thermistor was taped to the Si570 case and the heating resistor to the empty area of PCB nearby. The drift without the temp. control is about 50Hz day to night (or AC on and off), at 67.25MHz RX frequency. Si570 frequency is 4/3rd of that.
              Long-term stability with the oven on was great (within a few Hz), but depending on the ambient temperature there was sometimes "wandering", or slow oscillations with about 2 min period and 10-15Hz swing. I know this can be fixed by adjusting the gain and the time constant of the controller, but I gave up after having some fun with it :)

              73, Mike

              --- In softrock40@yahoogroups.com, "Alan" <alan4alan@...> wrote:
              >

              > My Softrock experiments all involve separating the Si570 from the Softrock so go against your minimal interference policy.
              > I made some improvement by putting the Si570 in an oven. I realised afterwards that I was probably being too cautious 40-50° was too
              > low. The internal temperature of a Si570 is going to be higher than that.
              > A few years ago there was discussion here, several tried thermistors on the Si570 case. I do not remember anyone giving details of
              > their results.
              >
            • cbayona
              Insulate the chip/thermistor with styrofoam so air cannot contact the assembly, it helps quite a bit. Cecil - k5nwa http://thepartsplace.k5nwa.com/
              Message 6 of 21 , May 22, 2013
              • 0 Attachment
                Insulate the chip/thermistor with styrofoam so air cannot contact the assembly, it helps quite a bit.

                Cecil - k5nwa
                http://thepartsplace.k5nwa.com/

                On May 22, 2013, at 9:58 AM, "vbifyz" <3ym3ym@...> wrote:

                > I tried "ovenizing" the Softrock (VHF version) without removing the Si570. The thermistor was taped to the Si570 case and the heating resistor to the empty area of PCB nearby. The drift without the temp. control is about 50Hz day to night (or AC on and off), at 67.25MHz RX frequency. Si570 frequency is 4/3rd of that.
                > Long-term stability with the oven on was great (within a few Hz), but depending on the ambient temperature there was sometimes "wandering", or slow oscillations with about 2 min period and 10-15Hz swing. I know this can be fixed by adjusting the gain and the time constant of the controller, but I gave up after having some fun with it :)
                >
                > 73, Mike
                >
                > --- In softrock40@yahoogroups.com, "Alan" <alan4alan@...> wrote:
                >>
                >
                >> My Softrock experiments all involve separating the Si570 from the Softrock so go against your minimal interference policy.
                >> I made some improvement by putting the Si570 in an oven. I realised afterwards that I was probably being too cautious 40-50° was too
                >> low. The internal temperature of a Si570 is going to be higher than that.
                >> A few years ago there was discussion here, several tried thermistors on the Si570 case. I do not remember anyone giving details of
                >> their results.
                >>
              • warrenallgyer
                I have finally been able to post photos of the mod on this forum at: http://groups.yahoo.com/group/softrock40/photos/album/1130144418/pic/list In addition to
                Message 7 of 21 , May 23, 2013
                • 0 Attachment
                  I have finally been able to post photos of the mod on this forum at:

                  http://groups.yahoo.com/group/softrock40/photos/album/1130144418/pic/list

                  In addition to the mechanical view I have put on two screen shots that show the phase noise of the Si5338 compared to the onboard Si5170. I don't yet understand all I know about phase noise but it seems that the less power in the sidebands, the better the phase noise performance of the oscillator.

                  I have not figured out how to quantify it from these pix but clearly the Si5170 seems to be better in that there are fewer sideband spurs and the total power would therefore be less.

                  In both cases however the level of the sidebands is 50 dB or better below the fundamental and I am not testing it on air on 20 meter WSPR with excellent results.

                  Clearly this is just an exercise because there is no operational benefit to this degree of frequency accuracy... but it does keep me (mostly) out of the bars.

                  Warren Allgyer - 9V1TD


                  > Warren,
                  >
                  > A few comments, not really relavent to your post but more to Softrock stability.
                  >
                  > I'd rather not join yet another group but would like to see your picture.
                  >

                  > 73 Alan G4ZFQ
                  >
                  >
                  >
                  >
                • Alan
                  ... Subject: [softrock40] Re: GPS Referenced RXTX for WSPR ... Warren, Jack has some tests of the Si570 near the bottom here
                  Message 8 of 21 , May 23, 2013
                  • 0 Attachment
                    ----- Original Message -----
                    Subject: [softrock40] Re: GPS Referenced RXTX for WSPR


                    >I have finally been able to post photos of the mod on this forum at:
                    >
                    > http://groups.yahoo.com/group/softrock40/photos/album/1130144418/pic/list
                    >
                    > In addition to the mechanical view I have put on two screen shots that show the phase noise of the Si5338 compared to the onboard
                    > Si5170. I don't yet understand all I know about phase noise but it seems that the less power in the sidebands, the better the
                    > phase noise performance of the oscillator.
                    >

                    Warren,

                    Jack has some tests of the Si570 near the bottom here <http://www.cliftonlaboratories.com/si570_kit_from_k5bcq.htm> I think that
                    quite good test gear is needed for this.
                    It seems there is not much that is any better than a Si570.
                    However, like GPS on HF:) is might be overkill in a Softrock?

                    >testing it on air on 20 meter WSPR with excellent results.
                    >
                    > Clearly this is just an exercise because there is no operational benefit to this degree of frequency accuracy...

                    Well, you are not the only one doing it because it is possible!

                    73 Alan G4ZFQ
                  • Michael Walker
                    While overkill, it is of value if you are using it for ARRL s Frequency Measurement Test. Besides, it is just fun to do it. Mike va3mw
                    Message 9 of 21 , May 23, 2013
                    • 0 Attachment
                      While overkill, it is of value if you are using it for ARRL's Frequency Measurement Test.

                      Besides, it is just fun to do it.

                      Mike va3mw



                      On Thu, May 23, 2013 at 6:34 AM, Alan <alan4alan@...> wrote:
                       


                      ----- Original Message -----
                      Subject: [softrock40] Re: GPS Referenced RXTX for WSPR

                      >I have finally been able to post photos of the mod on this forum at:
                      >
                      > http://groups.yahoo.com/group/softrock40/photos/album/1130144418/pic/list
                      >
                      > In addition to the mechanical view I have put on two screen shots that show the phase noise of the Si5338 compared to the onboard
                      > Si5170. I don't yet understand all I know about phase noise but it seems that the less power in the sidebands, the better the
                      > phase noise performance of the oscillator.
                      >

                      Warren,

                      Jack has some tests of the Si570 near the bottom here <http://www.cliftonlaboratories.com/si570_kit_from_k5bcq.htm> I think that
                      quite good test gear is needed for this.
                      It seems there is not much that is any better than a Si570.
                      However, like GPS on HF:) is might be overkill in a Softrock?


                      >testing it on air on 20 meter WSPR with excellent results.
                      >
                      > Clearly this is just an exercise because there is no operational benefit to this degree of frequency accuracy...

                      Well, you are not the only one doing it because it is possible!

                      73 Alan G4ZFQ


                    • John Williams
                      It is actually useful for us hams. I was told that K1JT s radio is GPS referenced so when I look at the spots, I tend to look for his call to see how far off
                      Message 10 of 21 , May 23, 2013
                      • 0 Attachment
                        It is actually useful for us hams. I was told that K1JT's radio is GPS referenced so when I look at the spots, I tend to look for his call to see how far off my radio is. Reported freq usually within 5 Hz of my vfo setting.

                        John - ke5ssh
                        On 5/23/2013 8:43 AM, Michael Walker wrote:
                         
                        While overkill, it is of value if you are using it for ARRL's Frequency Measurement Test.

                        Besides, it is just fun to do it.

                        Mike va3mw



                        On Thu, May 23, 2013 at 6:34 AM, Alan <alan4alan@...> wrote:
                         

                        ----- Original Message -----
                        Subject: [softrock40] Re: GPS Referenced RXTX for WSPR

                        >I have finally been able to post photos of the mod on this forum at:
                        >
                        > http://groups.yahoo.com/group/softrock40/photos/album/1130144418/pic/list
                        >
                        > In addition to the mechanical view I have put on two screen shots that show the phase noise of the Si5338 compared to the onboard
                        > Si5170. I don't yet understand all I know about phase noise but it seems that the less power in the sidebands, the better the
                        > phase noise performance of the oscillator.
                        >

                        Warren,

                        Jack has some tests of the Si570 near the bottom here <http://www.cliftonlaboratories.com/si570_kit_from_k5bcq.htm> I think that
                        quite good test gear is needed for this.
                        It seems there is not much that is any better than a Si570.
                        However, like GPS on HF:) is might be overkill in a Softrock?


                        >testing it on air on 20 meter WSPR with excellent results.
                        >
                        > Clearly this is just an exercise because there is no operational benefit to this degree of frequency accuracy...

                        Well, you are not the only one doing it because it is possible!

                        73 Alan G4ZFQ



                        -- 
                        
                        John Williams
                        
                        KE5SSH - ham since 2007
                        WQKA523 - GMRS for family use on the farm
                        
                      • alanzfq
                        ... John, My original comment about overkill related to the use of GPS to actually synchronise the RX/TX oscillator. A modern OCXO is, once setup, stable to
                        Message 11 of 21 , May 23, 2013
                        • 0 Attachment
                          --- In softrock40@yahoogroups.com, John Williams <KE5SSH@...> wrote:
                          >
                          > It is actually useful for us hams. I was told that K1JT's radio is GPS
                          > referenced


                          John,

                          My original comment about "overkill" related to the use of GPS to actually synchronise the RX/TX oscillator.
                          A modern OCXO is, once setup, stable to better than 0.1Hz at 10MHz.
                          So a very good accuracy may be maintained without need for a GPS system. Keeps it a little more simple.
                          I know several WSPR stations do use GPS, that, I say IS overkill. Or maybe not if actually used for research?

                          My method is merely to use a OCXO derived DDS to produce a marker so I know where I am. (And how much I drift).


                          >
                          > > While overkill, it is of value if you are using it for ARRL's
                          > > Frequency Measurement Test.

                          Mike,

                          Yes, a special purpose.
                          I wonder how close the winners get nowadays? Must be getting near the time the adjudicators have to allow for propagation effects?

                          > >
                          > > Besides, it is just fun to do it.
                          > >

                          And I don't disagree with that:)

                          73 Alan G4ZFQ
                        • Jack Smith
                          The Si570 screen capture by Warren shows a huge amount of 50 Hz power line contamination - you have to look only at the single spike in the center, not those
                          Message 12 of 21 , May 23, 2013
                          • 0 Attachment
                            The Si570 screen capture by Warren shows a huge amount of 50 Hz power line contamination - you have to look only at the single spike in the center, not those distributed +/- 50 Hz from the center.  The 50 Hz power line contamination is not attributable to the Si570's phase noise characteristics but rather resides elsewhere.

                            There's also a concern about broadband noise contamination that may mask close in phase noise.


                            Jack K8ZOA

                            On 5/23/2013 9:43 AM, Michael Walker wrote:
                             
                            While overkill, it is of value if you are using it for ARRL's Frequency Measurement Test.

                            Besides, it is just fun to do it.

                            Mike va3mw



                            On Thu, May 23, 2013 at 6:34 AM, Alan <alan4alan@...> wrote:
                             

                            ----- Original Message -----
                            Subject: [softrock40] Re: GPS Referenced RXTX for WSPR

                            >I have finally been able to post photos of the mod on this forum at:
                            >
                            > http://groups.yahoo.com/group/softrock40/photos/album/1130144418/pic/list
                            >
                            > In addition to the mechanical view I have put on two screen shots that show the phase noise of the Si5338 compared to the onboard
                            > Si5170. I don't yet understand all I know about phase noise but it seems that the less power in the sidebands, the better the
                            > phase noise performance of the oscillator.
                            >

                            Warren,

                            Jack has some tests of the Si570 near the bottom here <http://www.cliftonlaboratories.com/si570_kit_from_k5bcq.htm> I think that
                            quite good test gear is needed for this.
                            It seems there is not much that is any better than a Si570.
                            However, like GPS on HF:) is might be overkill in a Softrock?


                            >testing it on air on 20 meter WSPR with excellent results.
                            >
                            > Clearly this is just an exercise because there is no operational benefit to this degree of frequency accuracy...

                            Well, you are not the only one doing it because it is possible!

                            73 Alan G4ZFQ



                          • warrenallgyer
                            Jack Please help me, and maybe others on the group, understand what you see in the center spike that indicates 50 Hz contamination. I completely understand the
                            Message 13 of 21 , May 23, 2013
                            • 0 Attachment
                              Jack

                              Please help me, and maybe others on the group, understand what you see in the center spike that indicates 50 Hz contamination. I completely understand the sideband spurs space at 50 Hz... and GOOD CATCH on this, I had not noted the 50 Hz spacing.... but I am wondering what you see in the center spike that indicates trouble?

                              Also,.... is it really a huge amount of power? I am seeing very narrow spikes, spaced at 50 Hz intervals, which peak at a maximum of -50 dB from the center. How can I quantify the amount of power indicated?... and how much power is too much?

                              In no way arguing with you... just want to understand your reasoning.

                              Thanks!

                              Warren Allgyer - 9V1TD

                              --- In softrock40@yahoogroups.com, Jack Smith <Jack.Smith@...> wrote:
                              >
                              > The Si570 screen capture by Warren shows a huge amount of 50 Hz power
                              > line contamination - you have to look only at the single spike in the
                              > center, not those distributed +/- 50 Hz from the center. The 50 Hz
                              > power line contamination is not attributable to the Si570's phase noise
                              > characteristics but rather resides elsewhere.
                              >
                              > There's also a concern about broadband noise contamination that may mask
                              > close in phase noise.
                              >
                              >
                              > Jack K8ZOA
                              >
                              > On 5/23/2013 9:43 AM, Michael Walker wrote:
                              > > While overkill, it is of value if you are using it for ARRL's
                              > > Frequency Measurement Test.
                              > >
                              > > Besides, it is just fun to do it.
                              > >
                              > > Mike va3mw
                              > >
                              > >
                              > >
                              > > On Thu, May 23, 2013 at 6:34 AM, Alan <alan4alan@...
                              > > <mailto:alan4alan@...>> wrote:
                              > >
                              > >
                              > > ----- Original Message -----
                              > > Subject: [softrock40] Re: GPS Referenced RXTX for WSPR
                              > >
                              > > >I have finally been able to post photos of the mod on this forum at:
                              > > >
                              > > >
                              > > http://groups.yahoo.com/group/softrock40/photos/album/1130144418/pic/list
                              > > >
                              > > > In addition to the mechanical view I have put on two screen
                              > > shots that show the phase noise of the Si5338 compared to the onboard
                              > > > Si5170. I don't yet understand all I know about phase noise but
                              > > it seems that the less power in the sidebands, the better the
                              > > > phase noise performance of the oscillator.
                              > > >
                              > >
                              > > Warren,
                              > >
                              > > Jack has some tests of the Si570 near the bottom here
                              > > <http://www.cliftonlaboratories.com/si570_kit_from_k5bcq.htm> I
                              > > think that
                              > > quite good test gear is needed for this.
                              > > It seems there is not much that is any better than a Si570.
                              > > However, like GPS on HF:) is might be overkill in a Softrock?
                              > >
                              > >
                              > > >testing it on air on 20 meter WSPR with excellent results.
                              > > >
                              > > > Clearly this is just an exercise because there is no operational
                              > > benefit to this degree of frequency accuracy...
                              > >
                              > > Well, you are not the only one doing it because it is possible!
                              > >
                              > > 73 Alan G4ZFQ
                              > >
                              > >
                              > >
                              >
                            • Jack Smith
                              Warren: I did not mean to say that the central spike has 50 Hz contamination - rather that the spikes at +/- 50 Hz should be disregarded as they are not valid
                              Message 14 of 21 , May 23, 2013
                              • 0 Attachment
                                Warren:

                                I did not mean to say that the central spike has 50 Hz contamination - rather that the spikes at +/- 50 Hz should be disregarded as they are not valid to indicate anything about the phase noise. Those must not be used as an indication of Si570 phase noise but rather indicate problems with the receiver, power supply filtering, connecting cables, etc.

                                If you look at the central spike, you will see the typical spreading, but remember that the device the Si570 is driving (the receiver) has its own noise, e.g., 1/f noise for op-amps which can look a lot like PN on the oscillator.

                                So the most one can say is that the display indicates the sum of various noise sources, one being Si570, but the others being internal and external. For example, what is the PN of the signal source you used to obtain the 700 Hz beat note? The display is, of course, the sum of the PN of the Si570 local oscillator plus the PN of the signal source it mixes with to produce the 700 Hz beat note.

                                50/60 Hz line noise related noise in a good signal generator can be 90 dB down, or more, but that takes a great deal of attention to detail to achieve that. One of my HP 8657A signal generators has 60 Hz sidebands down 40 dB and a second HP 8657A has 60 Hz sidebands down 55 dB. But, my HP 8568B spectrum analyzer has 60 Hz sidebands down 80 dB or more as evidenced by observing a high quality 10 MHz oven time base, where I don't see 60 Hz sidebands above the noise floor.

                                Consequently before making any observations about PN of a particular device you MUST first establish the performance of the test equipment being used and verify its performance. To some degree this may seem circular, but it is possible to obtain useful performance information on the test gear without reference to the device under test.

                                Otherwise you are left in the position of not knowing what you see comes from the device being tested or represent artifacts of the test equipment. And once you characterize the test setup, you will still, of course, measure the sum (in some fashion, I don't necessarily mean linear sum) of the device under test and the test equipment.

                                The old rule of thumb used to be that if you intend to measure something to a precision of X, the test equipment should be 10x better so that the error contribution of the test equipment can be considered to be minimal. It may still need to be considered, but at least it does not dominate the measurement.

                                Jack K8ZOA
                                 
                                On 5/23/2013 1:07 PM, warrenallgyer wrote:
                                 

                                Jack

                                Please help me, and maybe others on the group, understand what you see in the center spike that indicates 50 Hz contamination. I completely understand the sideband spurs space at 50 Hz... and GOOD CATCH on this, I had not noted the 50 Hz spacing.... but I am wondering what you see in the center spike that indicates trouble?

                                Also,.... is it really a huge amount of power? I am seeing very narrow spikes, spaced at 50 Hz intervals, which peak at a maximum of -50 dB from the center. How can I quantify the amount of power indicated?... and how much power is too much?

                                In no way arguing with you... just want to understand your reasoning.

                                Thanks!

                                Warren Allgyer - 9V1TD

                                --- In softrock40@yahoogroups.com, Jack Smith <Jack.Smith@...> wrote:
                                >
                                > The Si570 screen capture by Warren shows a huge amount of 50 Hz power
                                > line contamination - you have to look only at the single spike in the
                                > center, not those distributed +/- 50 Hz from the center. The 50 Hz
                                > power line contamination is not attributable to the Si570's phase noise
                                > characteristics but rather resides elsewhere.
                                >
                                > There's also a concern about broadband noise contamination that may mask
                                > close in phase noise.
                                >
                                >
                                > Jack K8ZOA
                                >
                                > On 5/23/2013 9:43 AM, Michael Walker wrote:
                                > > While overkill, it is of value if you are using it for ARRL's
                                > > Frequency Measurement Test.
                                > >
                                > > Besides, it is just fun to do it.
                                > >
                                > > Mike va3mw
                                > >
                                > >
                                > >
                                > > On Thu, May 23, 2013 at 6:34 AM, Alan <alan4alan@...
                                > > <mailto:alan4alan@...>> wrote:
                                > >
                                > >
                                > > ----- Original Message -----
                                > > Subject: [softrock40] Re: GPS Referenced RXTX for WSPR
                                > >
                                > > >I have finally been able to post photos of the mod on this forum at:
                                > > >
                                > > >
                                > > http://groups.yahoo.com/group/softrock40/photos/album/1130144418/pic/list
                                > > >
                                > > > In addition to the mechanical view I have put on two screen
                                > > shots that show the phase noise of the Si5338 compared to the onboard
                                > > > Si5170. I don't yet understand all I know about phase noise but
                                > > it seems that the less power in the sidebands, the better the
                                > > > phase noise performance of the oscillator.
                                > > >
                                > >
                                > > Warren,
                                > >
                                > > Jack has some tests of the Si570 near the bottom here
                                > > <http://www.cliftonlaboratories.com/si570_kit_from_k5bcq.htm> I
                                > > think that
                                > > quite good test gear is needed for this.
                                > > It seems there is not much that is any better than a Si570.
                                > > However, like GPS on HF:) is might be overkill in a Softrock?
                                > >
                                > >
                                > > >testing it on air on 20 meter WSPR with excellent results.
                                > > >
                                > > > Clearly this is just an exercise because there is no operational
                                > > benefit to this degree of frequency accuracy...
                                > >
                                > > Well, you are not the only one doing it because it is possible!
                                > >
                                > > 73 Alan G4ZFQ
                                > >
                                > >
                                > >
                                >


                              • warrenallgyer
                                Thanks Jack. That is very clear and helpful. So, if I understand you correctly, I should be more concerned about the spreading of the central spike than about
                                Message 15 of 21 , May 23, 2013
                                • 0 Attachment
                                  Thanks Jack. That is very clear and helpful.

                                  So, if I understand you correctly, I should be more concerned about the spreading of the central spike than about the sidebands? That makes some sense to me. On the other hand, since the two signals under consideration are used as the LO in a receiver, both the spreading and the sidebands are introduced into and degrade the received signals.

                                  The receiver in this case is a Softrocks RXII HF so it does have a local Si5170 as well as op amps to consider.

                                  My intent here was to compare the Si5170 to the Si5338, not necessarily to quantify the PN so much as to quantify the difference between the two. That is why I have signals of the same level and frequency from the two devices.

                                  The fact that the Si5338 has more spreading on the central spike than does the Si5170, with identical receive conditions in both cases, indicates to me the presence of more phase noise. Right?

                                  If I could quantify the difference between the two, even if I could not quantify the noise absolutely, that would be a major step forward. Any thoughts?

                                  I can access real test equipment to do this but what is the fun in that? :-) . My goal is to be able to do meaningful measurements with simple tools; something that a majority of people would have access to.

                                  Warren Allgyer - 9V1TD



                                  --- In softrock40@yahoogroups.com, Jack Smith <Jack.Smith@...> wrote:
                                  >
                                  > Warren:
                                  >
                                  > I did not mean to say that the central spike has 50 Hz contamination -
                                  > rather that the spikes at +/- 50 Hz should be disregarded as they are
                                  > not valid to indicate anything about the phase noise. Those must not be
                                  > used as an indication of Si570 phase noise but rather indicate problems
                                  > with the receiver, power supply filtering, connecting cables, etc.
                                  >
                                  > If you look at the central spike, you will see the typical spreading,
                                  > but remember that the device the Si570 is driving (the receiver) has its
                                  > own noise, e.g., 1/f noise for op-amps which can look a lot like PN on
                                  > the oscillator.
                                  >
                                  > So the most one can say is that the display indicates the sum of various
                                  > noise sources, one being Si570, but the others being internal and
                                  > external. For example, what is the PN of the signal source you used to
                                  > obtain the 700 Hz beat note? The display is, of course, the sum of the
                                  > PN of the Si570 local oscillator plus the PN of the signal source it
                                  > mixes with to produce the 700 Hz beat note.
                                  >
                                  > 50/60 Hz line noise related noise in a good signal generator can be 90
                                  > dB down, or more, but that takes a great deal of attention to detail to
                                  > achieve that. One of my HP 8657A signal generators has 60 Hz sidebands
                                  > down 40 dB and a second HP 8657A has 60 Hz sidebands down 55 dB. But, my
                                  > HP 8568B spectrum analyzer has 60 Hz sidebands down 80 dB or more as
                                  > evidenced by observing a high quality 10 MHz oven time base, where I
                                  > don't see 60 Hz sidebands above the noise floor.
                                  >
                                  > Consequently before making any observations about PN of a particular
                                  > device you MUST first establish the performance of the test equipment
                                  > being used and verify its performance. To some degree this may seem
                                  > circular, but it is possible to obtain useful performance information on
                                  > the test gear without reference to the device under test.
                                  >
                                  > Otherwise you are left in the position of not knowing what you see comes
                                  > from the device being tested or represent artifacts of the test
                                  > equipment. And once you characterize the test setup, you will still, of
                                  > course, measure the sum (in some fashion, I don't necessarily mean
                                  > linear sum) of the device under test and the test equipment.
                                  >
                                  > The old rule of thumb used to be that if you intend to measure something
                                  > to a precision of X, the test equipment should be 10x better so that the
                                  > error contribution of the test equipment can be considered to be
                                  > minimal. It may still need to be considered, but at least it does not
                                  > dominate the measurement.
                                  >
                                  > Jack K8ZOA
                                  >
                                • Jack Smith
                                  Warren: If you reviewed two automobiles and one had four flat tires and the other didn t, would it be reasonable to say the first one did not handle well
                                  Message 16 of 21 , May 23, 2013
                                  • 0 Attachment
                                    Warren:

                                    If you reviewed two automobiles and one had four flat tires and the other didn't, would it be reasonable to say the first one did not handle well compared with the second, without mentioning the flat tires?

                                    Yes, 50 Hz sidebands are a problem -- BUT THEY DO NOT ORIGINATE IN THE SI570. Or if they do originate in the Si-570 section they are caused by a problem within your receiver. There is no mechanism within the Si-570 that causes 50 Hz sidebands as far as I know. I certainly saw no trace of those when I looked in some detail at the phase noise of an Si-570. Rather it indicates a deficiency elsewhere.

                                    So if you intend to compare the Si570 with the Si5338 you have failed if you focus on the 50 Hz sidebands. 

                                    You can either fix the 50 Hz contamination or ignore the 50 Hz sidebands. What you cannot do and produce an analysis that has credibility is to say those are part of the Si570's characteristic performance. They are in fact an artifact of your receiver or test signal or something else that I can't determine without more work than I care to spend on it.

                                    Before you take this further, you  really need to understand what PN is and how one measures it.

                                    Jack K8ZOA


                                    On 5/23/2013 8:20 PM, warrenallgyer wrote:
                                     

                                    Thanks Jack. That is very clear and helpful.

                                    So, if I understand you correctly, I should be more concerned about the spreading of the central spike than about the sidebands? That makes some sense to me. On the other hand, since the two signals under consideration are used as the LO in a receiver, both the spreading and the sidebands are introduced into and degrade the received signals.

                                    The receiver in this case is a Softrocks RXII HF so it does have a local Si5170 as well as op amps to consider.

                                    My intent here was to compare the Si5170 to the Si5338, not necessarily to quantify the PN so much as to quantify the difference between the two. That is why I have signals of the same level and frequency from the two devices.

                                    The fact that the Si5338 has more spreading on the central spike than does the Si5170, with identical receive conditions in both cases, indicates to me the presence of more phase noise. Right?

                                    If I could quantify the difference between the two, even if I could not quantify the noise absolutely, that would be a major step forward. Any thoughts?

                                    I can access real test equipment to do this but what is the fun in that? :-) . My goal is to be able to do meaningful measurements with simple tools; something that a majority of people would have access to.

                                    Warren Allgyer - 9V1TD

                                    --- In softrock40@yahoogroups.com, Jack Smith <Jack.Smith@...> wrote:
                                    >
                                    > Warren:
                                    >
                                    > I did not mean to say that the central spike has 50 Hz contamination -
                                    > rather that the spikes at +/- 50 Hz should be disregarded as they are
                                    > not valid to indicate anything about the phase noise. Those must not be
                                    > used as an indication of Si570 phase noise but rather indicate problems
                                    > with the receiver, power supply filtering, connecting cables, etc.
                                    >
                                    > If you look at the central spike, you will see the typical spreading,
                                    > but remember that the device the Si570 is driving (the receiver) has its
                                    > own noise, e.g., 1/f noise for op-amps which can look a lot like PN on
                                    > the oscillator.
                                    >
                                    > So the most one can say is that the display indicates the sum of various
                                    > noise sources, one being Si570, but the others being internal and
                                    > external. For example, what is the PN of the signal source you used to
                                    > obtain the 700 Hz beat note? The display is, of course, the sum of the
                                    > PN of the Si570 local oscillator plus the PN of the signal source it
                                    > mixes with to produce the 700 Hz beat note.
                                    >
                                    > 50/60 Hz line noise related noise in a good signal generator can be 90
                                    > dB down, or more, but that takes a great deal of attention to detail to
                                    > achieve that. One of my HP 8657A signal generators has 60 Hz sidebands
                                    > down 40 dB and a second HP 8657A has 60 Hz sidebands down 55 dB. But, my
                                    > HP 8568B spectrum analyzer has 60 Hz sidebands down 80 dB or more as
                                    > evidenced by observing a high quality 10 MHz oven time base, where I
                                    > don't see 60 Hz sidebands above the noise floor.
                                    >
                                    > Consequently before making any observations about PN of a particular
                                    > device you MUST first establish the performance of the test equipment
                                    > being used and verify its performance. To some degree this may seem
                                    > circular, but it is possible to obtain useful performance information on
                                    > the test gear without reference to the device under test.
                                    >
                                    > Otherwise you are left in the position of not knowing what you see comes
                                    > from the device being tested or represent artifacts of the test
                                    > equipment. And once you characterize the test setup, you will still, of
                                    > course, measure the sum (in some fashion, I don't necessarily mean
                                    > linear sum) of the device under test and the test equipment.
                                    >
                                    > The old rule of thumb used to be that if you intend to measure something
                                    > to a precision of X, the test equipment should be 10x better so that the
                                    > error contribution of the test equipment can be considered to be
                                    > minimal. It may still need to be considered, but at least it does not
                                    > dominate the measurement.
                                    >
                                    > Jack K8ZOA
                                    >


                                  • warrenallgyer
                                    Jack Gaining a better understanding PN was the point of my question. I am not focused at all on the 50 Hz sidebands. They are there, they are a problem. I am
                                    Message 17 of 21 , May 23, 2013
                                    • 0 Attachment
                                      Jack

                                      Gaining a better understanding PN was the point of my question.

                                      I am not focused at all on the 50 Hz sidebands. They are there, they are a problem. I am sure I can fix them. They are not an artifact of my receiver because the same receiver was used for both pix. They actually DO originate in the RXTX under test, if not in the 5170 itself then in the circuit that contains it.

                                      I actually have a pretty clear picture of what PN is.... what I am asking for is a simple way to judge it by comparing the two pix. I pointedly inquired about the fatness of the center signal, not the presence or levels of the sidebands.

                                      You clearly know more about this than I do. Otherwise I would not have asked.

                                      Thank you for your response.

                                      Warren Allgyer - 9V1TD


                                      --- In softrock40@yahoogroups.com, Jack Smith <Jack.Smith@...> wrote:
                                      >
                                      > Warren:
                                      >
                                      > If you reviewed two automobiles and one had four flat tires and the
                                      > other didn't, would it be reasonable to say the first one did not handle
                                      > well compared with the second, without mentioning the flat tires?
                                      >
                                      > Yes, 50 Hz sidebands are a problem -- BUT THEY DO NOT ORIGINATE IN THE
                                      > SI570. Or if they do originate in the Si-570 section they are caused by
                                      > a problem within your receiver. There is no mechanism within the Si-570
                                      > that causes 50 Hz sidebands as far as I know. I certainly saw no trace
                                      > of those when I looked in some detail at the phase noise of an Si-570.
                                      > Rather it indicates a deficiency elsewhere.
                                      >
                                      > So if you intend to compare the Si570 with the Si5338 you have failed if
                                      > you focus on the 50 Hz sidebands.
                                      >
                                      > You can either fix the 50 Hz contamination or ignore the 50 Hz
                                      > sidebands. What you cannot do and produce an analysis that has
                                      > credibility is to say those are part of the Si570's characteristic
                                      > performance. They are in fact an artifact of your receiver or test
                                      > signal or something else that I can't determine without more work than I
                                      > care to spend on it.
                                      >
                                      > Before you take this further, you really need to understand what PN is
                                      > and how one measures it.
                                      >
                                      > Jack K8ZOA
                                      >
                                      >
                                      > On 5/23/2013 8:20 PM, warrenallgyer wrote:
                                      > >
                                      > > Thanks Jack. That is very clear and helpful.
                                      > >
                                      > > So, if I understand you correctly, I should be more concerned about
                                      > > the spreading of the central spike than about the sidebands? That
                                      > > makes some sense to me. On the other hand, since the two signals under
                                      > > consideration are used as the LO in a receiver, both the spreading and
                                      > > the sidebands are introduced into and degrade the received signals.
                                      > >
                                      > > The receiver in this case is a Softrocks RXII HF so it does have a
                                      > > local Si5170 as well as op amps to consider.
                                      > >
                                      > > My intent here was to compare the Si5170 to the Si5338, not
                                      > > necessarily to quantify the PN so much as to quantify the difference
                                      > > between the two. That is why I have signals of the same level and
                                      > > frequency from the two devices.
                                      > >
                                      > > The fact that the Si5338 has more spreading on the central spike than
                                      > > does the Si5170, with identical receive conditions in both cases,
                                      > > indicates to me the presence of more phase noise. Right?
                                      > >
                                      > > If I could quantify the difference between the two, even if I could
                                      > > not quantify the noise absolutely, that would be a major step forward.
                                      > > Any thoughts?
                                      > >
                                      > > I can access real test equipment to do this but what is the fun in
                                      > > that? :-) . My goal is to be able to do meaningful measurements with
                                      > > simple tools; something that a majority of people would have access to.
                                      > >
                                      > > Warren Allgyer - 9V1TD
                                      > >
                                      > > --- In softrock40@yahoogroups.com
                                      > > <mailto:softrock40%40yahoogroups.com>, Jack Smith <Jack.Smith@> wrote:
                                      > > >
                                      > > > Warren:
                                      > > >
                                      > > > I did not mean to say that the central spike has 50 Hz contamination -
                                      > > > rather that the spikes at +/- 50 Hz should be disregarded as they are
                                      > > > not valid to indicate anything about the phase noise. Those must not be
                                      > > > used as an indication of Si570 phase noise but rather indicate problems
                                      > > > with the receiver, power supply filtering, connecting cables, etc.
                                      > > >
                                      > > > If you look at the central spike, you will see the typical spreading,
                                      > > > but remember that the device the Si570 is driving (the receiver) has
                                      > > its
                                      > > > own noise, e.g., 1/f noise for op-amps which can look a lot like PN on
                                      > > > the oscillator.
                                      > > >
                                      > > > So the most one can say is that the display indicates the sum of
                                      > > various
                                      > > > noise sources, one being Si570, but the others being internal and
                                      > > > external. For example, what is the PN of the signal source you used to
                                      > > > obtain the 700 Hz beat note? The display is, of course, the sum of the
                                      > > > PN of the Si570 local oscillator plus the PN of the signal source it
                                      > > > mixes with to produce the 700 Hz beat note.
                                      > > >
                                      > > > 50/60 Hz line noise related noise in a good signal generator can be 90
                                      > > > dB down, or more, but that takes a great deal of attention to detail to
                                      > > > achieve that. One of my HP 8657A signal generators has 60 Hz sidebands
                                      > > > down 40 dB and a second HP 8657A has 60 Hz sidebands down 55 dB.
                                      > > But, my
                                      > > > HP 8568B spectrum analyzer has 60 Hz sidebands down 80 dB or more as
                                      > > > evidenced by observing a high quality 10 MHz oven time base, where I
                                      > > > don't see 60 Hz sidebands above the noise floor.
                                      > > >
                                      > > > Consequently before making any observations about PN of a particular
                                      > > > device you MUST first establish the performance of the test equipment
                                      > > > being used and verify its performance. To some degree this may seem
                                      > > > circular, but it is possible to obtain useful performance
                                      > > information on
                                      > > > the test gear without reference to the device under test.
                                      > > >
                                      > > > Otherwise you are left in the position of not knowing what you see
                                      > > comes
                                      > > > from the device being tested or represent artifacts of the test
                                      > > > equipment. And once you characterize the test setup, you will still, of
                                      > > > course, measure the sum (in some fashion, I don't necessarily mean
                                      > > > linear sum) of the device under test and the test equipment.
                                      > > >
                                      > > > The old rule of thumb used to be that if you intend to measure
                                      > > something
                                      > > > to a precision of X, the test equipment should be 10x better so that
                                      > > the
                                      > > > error contribution of the test equipment can be considered to be
                                      > > > minimal. It may still need to be considered, but at least it does not
                                      > > > dominate the measurement.
                                      > > >
                                      > > > Jack K8ZOA
                                      > > >
                                      > >
                                      > >
                                      >
                                    • John Rabson
                                      Where do the 50 Hz side bands originate? Presumably not mains-related as in North America one would expect 60 Hz. John F5VLF
                                      Message 18 of 21 , May 24, 2013
                                      • 0 Attachment
                                        Where do the 50 Hz side bands originate? Presumably not mains-related as in North America one would expect 60 Hz.

                                        John F5VLF

                                        On 24 May 2013, at 02:48CEST, Jack Smith wrote:

                                        > Warren:
                                        >
                                        > If you reviewed two automobiles and one had four flat tires and the other didn't, would it be reasonable to say the first one did not handle well compared with the second, without mentioning the flat tires?
                                        >
                                        > Yes, 50 Hz sidebands are a problem -- BUT THEY DO NOT ORIGINATE IN THE SI570. Or if they do originate in the Si-570 section they are caused by a problem within your receiver. There is no mechanism within the Si-570 that causes 50 Hz sidebands as far as I know. I certainly saw no trace of those when I looked in some detail at the phase noise of an Si-570. Rather it indicates a deficiency elsewhere.
                                        >
                                        > So if you intend to compare the Si570 with the Si5338 you have failed if you focus on the 50 Hz sidebands.
                                        >
                                        > You can either fix the 50 Hz contamination or ignore the 50 Hz sidebands. What you cannot do and produce an analysis that has credibility is to say those are part of the Si570's characteristic performance. They are in fact an artifact of your receiver or test signal or something else that I can't determine without more work than I care to spend on it.
                                        >
                                        > Before you take this further, you really need to understand what PN is and how one measures it.
                                        >
                                        > Jack K8ZOA
                                      • warrenallgyer
                                        ... I live in Singapore..... and it is very likely mains related. Warren Allgyer - 9V1TD
                                        Message 19 of 21 , May 24, 2013
                                        • 0 Attachment
                                          :-)

                                          I live in Singapore..... and it is very likely mains related.

                                          Warren Allgyer - 9V1TD

                                          --- In softrock40@yahoogroups.com, John Rabson <john.rabson@...> wrote:
                                          >
                                          > Where do the 50 Hz side bands originate? Presumably not mains-related as in North America one would expect 60 Hz.
                                          >
                                          > John F5VLF
                                          >
                                          > On 24 May 2013, at 02:48CEST, Jack Smith wrote:
                                          >
                                          > > Warren:
                                          > >
                                          > > If you reviewed two automobiles and one had four flat tires and the other didn't, would it be reasonable to say the first one did not handle well compared with the second, without mentioning the flat tires?
                                          > >
                                          > > Yes, 50 Hz sidebands are a problem -- BUT THEY DO NOT ORIGINATE IN THE SI570. Or if they do originate in the Si-570 section they are caused by a problem within your receiver. There is no mechanism within the Si-570 that causes 50 Hz sidebands as far as I know. I certainly saw no trace of those when I looked in some detail at the phase noise of an Si-570. Rather it indicates a deficiency elsewhere.
                                          > >
                                          > > So if you intend to compare the Si570 with the Si5338 you have failed if you focus on the 50 Hz sidebands.
                                          > >
                                          > > You can either fix the 50 Hz contamination or ignore the 50 Hz sidebands. What you cannot do and produce an analysis that has credibility is to say those are part of the Si570's characteristic performance. They are in fact an artifact of your receiver or test signal or something else that I can't determine without more work than I care to spend on it.
                                          > >
                                          > > Before you take this further, you really need to understand what PN is and how one measures it.
                                          > >
                                          > > Jack K8ZOA
                                          >
                                        Your message has been successfully submitted and would be delivered to recipients shortly.